References


1.       Swanson, A.B. Implant arthroplasty for the great toe joint.  Clin. Orthop. 85:75-81, 1972.

2.       Kampner, S.L. Total joint replacement in bunion surgery.  Orthopedics 1:275-284, 1978.

3.       Niebauer, J.J., Shaw, J.L., Doren, W.W.  This silicone-dacron hinge prosthesis.  Design evaluation and application, J. Bone Joint Surg. 50a:634, 1968.

4.       Arenson, D.J.  The angled great toe implant (Swanson design/Well modification) in the surgical reconstruction of the first metatarsophalangeal joint.  Clin. Podiatr. 1:89-102, 1984.

5.       La Porta, G.A., Pilla, P., Richter, K.P. Keller implant procedure:  a report of 536 procedures using a SILASTIC intramedullary stemmed implant J.A. P.A. 6:126-146, 1976.

6.       Vanore, J.A., O’Keefe, R.G., Pikscher, I.  First metatarsophalangeal joint athroplasty.  In Comprehensive Textbook of Foot Surgery, 2nd ed. Pp. 617-684, Williams & Wilkins Co., Baltimore, 1992.

7.       Bass, S.J., Gastwirth, C.M., Green, R., Knights, E.M., Weinstock, R.E. Phagocytosis of SILASTIC material following SILASTIC great toe implant. J. Foot Surg. 17:70-72, 1978.

8.       Shereff, M.J., Jahss, M.H. Complications of SILASTIC implant arthroplasty and synovitis; complications of silicone elastomer finger joint prosthesis. J.A. M.A. 237:1463-1544, 1977.

9.       Christie, A.J., Weinberger, K.A., Dietrich, M. Silicone lymph-adenopathy and synovitis; complications of silicone elastomer finger joint prosthesis J.A. M.A. 237:1463-1544, 1977.

10.   Kircher, T. Silicone lymphadenopathy: a complication of silicone elastomer finger joint prosthesis.  Human Pathol. 11:240-244, 1980.

11.   Weinstock, R.E., Bass, S.J., Wolfson, A.F., Sorkin, B.A. Osseous engulfment of a silicone prosthesis with foreign body reaction.  J.A. P.A. 74:80-88, 1984.

12.   Verhaar, J., Bulstra, S., Walenkamp, G. Silicone arthroplasty for hallux rigidus, implant wear and osteolysis.  Acta Orthop. Scand. 60:30-33, 1989.

13.   Verhaar, J., Vermeulen A., Bulstra, St., Walenkamp, G. Bone reaction to silicone metatarsophalangeal joint-1 hemiprosthesis.  Clin. Orthop. Rel. Res. 245:228-232, 1989.

14.   Bonsal, M., Goldman, A.B., Bullough, P.G., Masearenhas, B. Case Report 706.  Skel. Radiol. 21:49-51, 1992.

15.   McDonald, R.J., Griffin, J.M., Edelman, R.O. Consecutive bilateral failures of the first metatarsophalangeal joint prosthesis.  J. Foot Surg. 25:226-233, 1986.

16.   McCarthy, D.J., Chapman, H.L. Ultrastructure of collapsed metatarsophalangeal silicone elastomer implant.  J. Foot Surg. 27:418-427, 1988.

17.   Kitaoka, H.B., Cracchiolo III, A. Stress fracture of the lateral metatarsals following double stem silicone implant arthroplasty of the hallux metatarsophalangeal joint.  Clin. Orthop. Rel. Res. 239:211-216, 1989.

18.   Jay, R.M., Shoehaus, H.D. Complications in implant arthroplasties for the osteoarthritic joint.  J.A. P.A. 72:248-254, 1982.

19.   Wanivenhaus, A., Lintner, F., Wurnig, C., Missaghi-Schinzl, M. Long term reaction of the osseous bed around silicone implants.  Arch. Orthop. Trauma Surg. 110:146-150, 1991.

20.   Yamashina, M., Moatamad, F. Peri-articular reactions to microscopic erosion of silicone-polymer implants.  Am. J. Surg. Pathol. 9:215-219, 1985.

21.   Gordon, M., Bullough, P.G. Synovial and osseous inflammation in failed silicone rubber prosthesis.  J. Bone Joint Surg. 64a:574-580, 1982.

22.   Sollitto, R.J., Shonkweiler, W. Silicone shard formations: a product of implant arthroplasty.  J. Foot Surg. 23:362-365, 1984.

23.   McCarthy, D.J., Kershisinik, W., O’Donnell, E.  The histopathology of silicone elastomer implant failure in podiatric surgery.  J.A. P.M.A.. 76:247-265, 1986.

24.   Jasim, K.A., Wecrasinghe, B.D. Silicone lymphadenopathy, synovitis and osteitis complicating big toe SILASTICâ prostheses, J. Royal Coll. Surg. Edinburgh 32:29-33, 1987.

25.   Sheil, W.C. Jason, M. Granumlomatous inguinal lymphadeopathy after bilateral metatarsophalangeal joint silicone arthroplasty, Foot Ankle 6:216-218, 1986.

26.   Lim, W.T., Landrum, K., Weinberger, B. Silicone lymphadenitis secondary to implant degeneration.  J. Foot Surg. 22:243-246, 1983.

27.   Sherey, W.J., Urbaniak, J.R., Polissan, R.P. Silicone synovitis: clinical, radiologic and histologic feature.  South Med. J. 82:1156-1158,1989.

28.   Rogers, L.A., Longtine, J.A., Garnick, M.B., Pinkus, G.S.  Silicone lymphadenopathy in a long distance runner: complication of a SILASTICâ prosthesis.  Human Pathol. 19:1237-1239, 1988.

29.   Travis, W.D., Balogh, K., Abraham, J.L. Silicone granulomas: report of three cases and review of the literature.  Human Pathol. 1:19-27, 1985.

30.   Atkinson, R.E., Smith, R.J. Silicone synovitis following silicone implant arthroplasty.  Complications of hand surgery.  Hand Clin. 2:291-299, 1986.

31.   Granberry, W.M., Noble, P.C., Bishop, J.O., Tullos, H.S. Use of a hinged silicone prosthesis for replacement arthroplasty of the first metatarsophalangeal joint J. Bone Joint Surg. 73a:1453-1459, 1991.

 

Additional Referrences

Koenig, R.D. Total great toe implant, preliminary report, J.A.P. M.A. 80:462-468, 1990.
Swanson, A.B., DeGroot Swanson, G., Frisch, E. Flexible (silicone) implant arthroplasty in the small joint of extremeties: concepts, physical and biological considerations, experimental and clinical results.  Biomaterials in Reconstructive Surgery, p. 595, CV Mosby, St. Louis, 1983.
Vanore, J.V., O’Keefe, R., Pikscher, I. First metatarsophalangeal joint implant arthroplasty, Ch. 24.  In Comprehensive Textbook of Foot Surgery, vol. 2, pp. 756-807, Williams & Wilkins Co., Baltimore, 1987.

Revision Arthroplasty Utilizing

The BiometTotal Toe System for Failed Silicone Elastomer Implants

The Biomet Total Toe System

Utilizing the Koenig Score: A Five Year Review

Methodology

Seventeen patients were selected for the study, each requiring a metatarsophalangeal joint arthroplasty.  One of the patients in the study discontinued care 2 months after the surgery.  All of the patients were in good health and were considered excellent surgical candidates, classified as category II or above on the American Society of Anesthesiologists Physical Status scale. Category II is described as mild systematic disease with no functional disorder.

Dorsoplantar and lateral x-rays were taken during weightbearing and in the angle and base of gait.  Intermetatarsal angles and hallux abductus angles were measured from the dorsoplantar x-ray view, using and MDMÒ2 tractograph.  The first metatarsal length was measured at the midline axis from the head to the base in both dorsoplantar and lateral x-ray views, then averaged.  Range of motion was measured from the resting state of the first metatarsophalangeal joint, with the foot in the neutral position, as described by Farnworth et al.2  Measurements were made in triplicate and averaged.  An OECÒ2 goniometer was used while the patient was seated with the legs extended.  Gait was observed, and hallux ground purchase was recorded by observing the ability of the patient to blanch the nail bed of the hallux while standing.
Postoperatively, reduction in complaint of pain was based on a visual analog scale of 1 through 10.3
X-rays in the dorsoplantar and lateral views were taken immediately postoperative, and at 2 weeks, 6 weeks, (Figs. 8 and 9), 12 weeks, 24 weeks, 36 weeks, 52 weeks, and 72 weeks.  Postoperative x-ray measurements were made using the same techniques as preoperatively.  Metatarsal length was measured in serial fashion to determine from observing contact of implant on bone from the weightbearing lateral x-rays.  The metatarsal seat was rated as: type 1, correct position, full contact with bone, all surfaces; type 2, correct position, one surface without a seat; type 3, angulated with full contact all surfaces; and type 4, poor position, no seat.
 

Figure 4.  The cutting guide is secured with two Kirschner wires and a bone clamp.  Note: the guide must be in the sagittal plane and aligned with the long axis of the metatarsal.

Figure 5.  The four metatarsal cuts are completed medial to lateral and checked with a frontal plane guide.

Figure 6.  The intramedullary hole is drilled, enlarged, and made rectangular with the system’s intramedullary metatarsal broach.

Toe-ground purchase was evaluated at 3 months postoperatively and serially observe, with improvement value superseding the last recorded value.  The findings were rated as: 1) full ground purchase; 2) ground contact, but no pressure; and 3) no ground contact.

Findings


Sixteen patients with 18 Koenig implants were evaluated during an 18-month period.  The patients’ ages ranged from 25 years to 73 years, with a mean age of 55.46 years.
Table 1 is a visual analog scale, presented to the patients preoperatively and postoperatively.  Preoperatively, all of the patients indicated that they were number 10 on the analog scale.  All of the patients indicated they were free of pain in the first metatarsophalangeal joint postoperatively.
Table 2 presents preoperative and postoperative values for the numerous parameters.  The mean preoperative range of motion was 17.63°.  The mean postoperative range of motion was 50.05°, for a net gain of 32.42° (Fig. 10).  Hallux purchase, postoperatively, was type 1 for 12 of the 18 cases (66.6%), type 2 for three cases (16.6%), and type 3 for three cases (16.6%).  The metatarsal implant component seat was type 1 for seven cases, type 2 for four cases, type 3 for six cases, and type 4 for one case.











Table 1. Visual Analog Pain Scale

Weight bearing reproduces pain upon arising from rest

(Preoperative pain)

                                                    10

                                                     9

                                                     8

                                                     7

                                                     6

Afternoon pain, active day

                                                     6

                                                     4

                                                     3

Night Trouble

                                                     2

                                                     1

No Pain

                                                     0

 

Figure 7.  The proximal phalanx is treated in the same way as the metatarsal.

Figure 8.  Six weeks postoperative radiograph, dorsoplantar view of first metatarsophalangeal joint demonstrating Koenig implant arthroplasty.

Figure 9.  Six weeks postoperative radiograph, lateral view of first metatarsophalangeal joint demonstrating Koenig implant arthroplasty.

Preoperative & Postoperative Measurements

Table 3 presents preoperative and postoperative first metatarsal lengths.  Measurements postoperatively were made at regular intervals and were averaged after being serially compared.  The mean preoperative length was 63.68 mm and the mean postoperative length was 62 mm, a net loss of 1.68 mm.
 

Discussion


All of the patients who remained in the study reported satisfactory elimination of painful loss of motion of the great toe joint.  A 39% mean increase of motion was achieved early in the study (3 months).  A 45° increase in range of motion was achieved in those patients with a 1-year postoperative examination.  In 83% of the cases studied, there was improvement in the ability of the hallux to purchase and press the ground.

Metatarsal length comparison was studied to determine the effect of a weightbearing, press-fit, metallic implant on host bone.  Because of previous experiences with implant sinking and engulfment, the Koenig implant has full cortical coverage and a large contact face, thus spreading forces over a greater area than previously designed implants.  Due to the design properties of the plantar shelf, full weightbearing and activity was achievable without evidence of loosening or dislodgment of the metatarsal component.  Measuring and comparing length of the first metatarsal was a means of evaluating bone absorption from irritation or bone stimulation by increasing forces.  No significant change in length indicated host-bone acceptance.  Variables existed, which had to be considered, including the 3-mm gain for the thickness of the metatarsal component articular surface; and adjunctive procedures, ie, five cases of closing wedge osteotomies (average loss of 3 mm), two cases of metatarsal head resection (average resection 8-mm loss plus 3-mm gain with implant, for a net loss of 5-mm), and one case of bone graft (5-mm gain) for repair of a previous Mayo bunionectomy.

After 24 months, no implants have sunk into the first metatarsal or the base of the great toe, and no reactive bone has engulfed either component.  The first implantation has shown early signs of loosening at one content surface, the dorsum of the metatarsal.  This is attributed to the implantation being performed prior to the development of specific instrumentation.  At 72 weeks, no patients exhibited osteophytosis about the implant.
 
Gait was studied postoperatively and recorded on film.  A slow-motion review of the film showed two important features: 1) patients were able to bear weight on the first metatarsal, thus improving gait; and 2) motion was not constrained in any of the three planes of motion, ie, dorsiflexion and plantarflexion, great toe angulation, and supination of the first metatarsal during weight acceptance and weight transfer.
 
The choice of biomaterial was considered, with preference for titanium alloy and ultra high molecular weight polyethylene.  Titanium alloy is highly biocompatible and resistant to corrosion.  Titantium alloy has a high weight-to-strength ratio and has an elastic modulus only 8 times greater than that of bone.4  Ultra high molecular weight polyethylene is frequently used in orthopedic surgery for its reliable compatibility with metallic implants.  It has high impact resistance and resistance to stress cracking.  It also has resistance to chemical attach and low friction modulus with metal.5

Case 10 required revision of the first metatarsal at 8 months postoperatively.  An 8-mm section of the metatarsal head was sent to pathology and histologic slides were reviewed.  Minimal metalosis (titanium oxide crystals) was identified.  Few inflammatory cells were found.  Normal new bone activity was seen.  A typical passive coating was seen where the implant contacted host tissue.

Conclusion


This is a preliminary report of 16 patients (18 implants) with degenerative joint disease.  These patients were all treated with a fully weightbearing first metatarsophalangeal joint implant.  The two-component implant has demonstrated a wide variety of application with predictably good relief of symptoms.  The procedure was successful in achieving a good range of motion.  It increased great toe purchase ability.  The implant demonstrated no compromise to host bone.  The postoperative inflammatory response was short and of small magnitude because of superior biomaterials.  Special instrumentation makes accurate surgical installation reproducible and predictable.

References


1.Swanson AB, Biddulph SI, Hagert CG: A silicone rubber implant to supplement the Keller toe arthroplasty.  NY Univ Inter-Clin Inform Bull 10: 7, 1971.

2.Farnworth C, Haggard S, Nahmias MC ET AL: The LaPorta great toe implant.  A preliminary study of its efficacy, JAPMA 76: 625, 1986.

3.Scott J, Huskisson EC: Graphic representation of pain.  Pain 2: 175, 1976.

4.Bannon BP, Mild EE: Titanium Alloys in Surgical Implants, Americal Society for Testing and Materials, Phoenix, 1981.

5.Bloch B Hastings GW, EDS: Plastics Materials in Surgery, 2nd ed, Charles C Thomas, Springfield, IL, 1972.


Additional Reference

Miller RD, ED: Anesthesia, 2nd Ed, Vol 1, Churchill Livingstone, Inc., New York, 1986.

 



The silicone elastomer implant for small joint reconstruction was introduced by Dr. Alfred Swanson (1).  Initially, the implant’s advocates enjoyed enthusiasm for the small, flexible nonfixated prosthesis.  It was easy to implant with fairly predictable results and increased range of motion.  Those with concern for implant dislodgement attempted to tie the implant to bone (2).  Others integrated the implant with dacron mesh to attempt ingrowth to bone tissue (3).  The design was angulated (4), hinged (2), and abuttment surfaceds were integrated to protect the implant from abrasion by cut edges of bone, as well as prevent aggressive cortical bone from engulfing the implant, and thus cause pseudoarthrosis (5).  Most recently, titanium grommets have been added to the procedure to protect the soft implant from bone abrasion leading to particularization and early wear, resulting in failure (6).

During the early 1980s, reports of premature wear began to appear in the literature (7-20).  By the mid-1980s, more serious concerns were raised about silicone synovitis, the result of abrasion of the implants producing microscopic particles introduced into synovial tissues (Fig. 1).  To a greater extent was concern for silicone particulate lymphandenitis; cystic changes from cancellous bone adjacent to these implants (Fig. 2), and cortical lysis due to low grade chronic inflammation from micromotion of the implant in bone (21-30) (Fig. 3).
 

The author presents a 3-year study of 10 cases of revisional arthroplasty utilizing the Biomet Total Toe System.    The procedure is performed to eliminate pain and restore function in cases of metatarsophalangeal joint silicone elastomer implant failure.  The surgeon should be familiar with the Total Toe System before attempting revision.


Richard D. Koenig, DPM, FACFAS1

Figure 1.  Synovial lining with silicone particulate (A) silicone, (B) giant cell engulfment of silicone particle (H & E x400).

Figure 2.  Failure of silicone arthoplasty with fracture of metatarsal condylar component.  Cancellous lysis adjacent to XXX.  A, anteroposterior; B, lateral views.

Figure 3.  SILASTICâ great toe prosthesis arthroplasty, 5 XXX postoperative.  Implant ruptured at stem-interface.  Cancellous bone lysis adjacent to stem.  Lysis of cortical bone at implant-bone interface.  Irregular metatarsal surfaces with reactive hypertrophy and cold flow deformity (an uneven pressure deforming force) of the interface.

Retrieval of the worn implant may be appropriate, but, revision of the badly worn joint margins is potentially difficult (Fig. 4).  Fusion is a viable option; however, the bone may be cystic.  The frontal plane edges and created intramedullary canal are covered with a fibrous membrane with varying degrees of inflammation, some of which is foreign body reaction (Fig. 5).  The membrane includes synovial cells.  Often, the metatarsal and the proximal phalanx are compromised in length.  Revision by means of reimplantation may be considered.
Since 1989, 10 cases of silicone elastomer implant arthroplasty have been revised by the author utilizing the Biomet Total Toe Systemâ2.  Strict criteria for surgical candidacy was established.  The patient had to have severe wear of the silicone elastomer implant (Fig. 6) and painful motion.  Brittle diabetic patients, vascularly impaired patients and osteoporotic patients were unsuitable.  Patients who were active, desirous of walking without discomfort, limping, or exhibited unnecessary stiffness in the great toe joint were considered candidates.

Operative Technique
A medial incision is employed to expose the first metatarsophalangeal joint.  It is important to exercise care underscoring the capsule, as this structure should be closed meticulously when the arthroplasty is completed.  Both sides of the failed silicone implant are removed.  This exposes the fibrous membrane that covers the ends of the metatarsal and phalanx as well as the intramedullary canals (Figs. 5, 7). 
 

Figure 4.  Three-year postoperative flexible hinge SILASTICâ implant arthroplasty with severe damage to implant, profound hypertrophy – cancellous lysis adjacent to stems.  The removal of lateral sesamoids like this is recommended.

This membrane must be removed in its entirety.  It will serve as a buffer between bone and implant and prevent ongrowth of bone to implant, therefore causing a surgical failure.  It is recommended to remove the exposed ends of the metatarsal with the cutting block (Fig. 8).  This will save time and dissection efforts.
 
The medial eminence should be recut superficially to allow application of the cutting block.  With the block held firmly in place by three 0.045-inch Kirschner wires,3 remove only enough metatarsal head to ensure that the fibrous membrane is absent.  Consider that the membrane will grow into the cancellous bone by varying depths.  The lining in the intramedullary canals is easily removed with a bone currette.  Removal of approximately 2-mm. Of the proximal phalanx should detach the membrane from the that structure.
The author recommends that the lateral sesamoid, if present, be removed in all cases.  In a diseased state, the lateral sesamoid will reduce postoperative range of motion.  The medial sesamoid, normally approximately 3 to 4 mm., may hypertrophy to 5 to 6 mm.  It should be planed to reduce its bulk and deformed articulating edges.
Cancellous allografts are moistened and gently pressed into the intramedullary canals (Fig. 9).  Trim the grafts to better fit the tapered holes.  The grafts are then compressed by tapping them in with the phalangeal broaches from The Total Toe System’s instrumentation (Fig. 10).  Once again, fill the holes with another cubed graft until flush with the edge of bone.  Retap the intramedullary hole in the repaired cancellous bone, using the frontal plane drill guides (Fig. 11).  Low speed drilling with a 1.5 twist drill bit will prevent shattering of the cancellous grafts (Fig. 12).  The use of metatarsal and phalangeal broaches is discretionary; however, in most cases it is not necessary.  The cancellous allografts are soft enough to compress with the stem of the implants.


The metatarsal implant should be installed first.  Insert the stem and tap gently with the polyethylene faced driver and mallet.  The phalangeal component is installed by hand and pressed to seat by retrograde pressure of the hallux.  Articulate the components and examine range of motion and alignment (Figs. 13-15).  It may be necessary to balance the medial and lateral capsule.  The intermetatarsal angle should be within normal parameters or reduced by osteotomy. 
 

Figure 5.  The membrane lining the intramedullary canal is easily curretted (arrow).  This membrane will contain synovial cells in fibrous tissue with inflammatory cells.

Figure 6.   Retrieved SILASTICâ implant during revision.  Note damage to hinge, loss of SILASTICâ material and “buffing” at interface surfaces.  Injury to the stem is a common finding at retrieval.

Figure 7.  The membrane lining the intramedullary canal must be removed.

Figure 8.  Cutting block from Biomet Total Toe System’s instrumentation.  This block called a capture jig, controls excursion of saw blade for accuracy.

Figure 9.  Cancellous allograft pressed into prepared intramedullary canal.

Proper use of this implant will not stabilize joint alignment.  The capsule is closed with small absorbable sutures and the skin is closed by conventional measures.  A thin dressing is applied for consideration of continuous passive motion machinery. 

  Subcapsular shortacting steroids are employed to reduce joint swelling, and intravenous antibiotics (usually 1 gm. Ancef IV) are given intraoperatively.
 

Results


All 10 cases had an uneventful recovery.  Patients were maintained at home for 72 hr. following surgery.  They were allowed bathroom and dining room privileges, otherwise were confined to rest and elevation.

Continuous passive motion4 was instituted the evening of surgery, while local anesthesia was still in effect.
 

Figure 10.  The allograft is pressed into  the intramedullary canal with the phalangeal broach from the Biomet  Total Toe System’s instrumentation.

Figure 11. The frontal plane drill guide from the Biomet Total Toe System's instrumentation centers the new intramedullary canal and examines the sagittal plane cuts

Figures 12.  Drilling the intramedullar canal in the allograft preserves the integrity of the graft.

Figure 13.  Revision arthroplasty in full dorsiflexion.

Figure 14.  Revision arthroplasty in full plantar flexion.

Figure 15.  Revision athroplasty in neutral position.

Figure 16.  Two-year postoperative revision of silicone implant failure (see preoperative Fig. 2).  A, anteroposterior; B, lateral views.

Continuous passive motion was administered for 20- to-30-min. sessions five to six times per day.  Angle settings and velocity were set to patient tolerance.  Therapy was ordered for 4 to 6 weeks.  Where patient compliance was thought to be challenging, a below-the-knee nonweightbearing cast was applied, to restrict patient activities.  The distal end of the cast stopped at the metatarsal anatomical neck to allow use of continous passive motion.  Sutures were removed at 14 days, and casts at 24 days.  X-rays were taken in standing dorsoplantar and lateral positions at presurgical consultation, immediately postoperative and at 2, 6, 16, and 52 weeks.
Nine cases healed successfully.  Success was defined as 1 or more years with no pain from the first metatarsophalangeal joint, full return to daily activities without compromise of activity and radiographic evidence that the implants were not loose or causing undesirable bone reaction, i.e., hypertrophy, shortening or cystic changes in bone as a result of the revision implantation (Fig. 16).  Two cases involved first metatarsal allograft with implantation.  The earlier allograft/implant revision involved lengthening of an extremely shortened metatarsal by a distal metarsal neck graft with the metatarsal component cemented to the allograft.  At 14 months the graft failed to take and the implant and graft were removed.  The patient elected not to have further surgery.
 

Conclusion


The objectives of arthroplasty of any joint are relief of pain and restoration of as much function of the joint as possible (31).  Revision implant surgery of the first metatarsophalangeal joint is not unlike large joint reconstruction.  The implant must be of functional design and constructed of durable materials because, at best, the failed silicone arthroplasty yields a compromised joint.  Six of the 10 surgical candidates had two prior surgeries, therefore the revision had to be precise.  Fusion of the first metatarsophalangeal joint, a viable option, must be considered but was ruled out by this author because the patient’s needs favor more flexibility, as well as the bone quality would not support successful fusion.
 
The Biomet Total Toe System has allowed for the retrieval of failed silicone elastomer implants, joint surface replacement on both sides of the great toe joint, and improved range of motion.  In addition, the system has improved range of motion.  In addition, the system has allowed return to full weightbearing of the metatarsal head, ability to remodel the remaining sesamoid, maintenance of first ray length and full cortical coverage on both sides of the joint to prevent further intra-articular deformity.  For 3 years, the Biomet Total Toe System has demonstrated successful results in revision of failed silicone elastomer arthroplasties of the first metatarsophalangeal joint, where it is the patient’s desire to have restored function in the ball of the foot.
 

The two-component, durable first metatarsophalangeal joint implant has a 5-year history of clinical use.  Unique for having plantar condyles, the Total Toe System is fully weightbearing, thus functional.  A new scoring system, the Koenig Score, is introduced and applied to the Biomet Total Toe System to demonstrate the success of this implant postoperatively.  (The Journal of Foot and Ankle Surgery 35 (1): 23-26, 1996)

Key words: metatarsophalanageal joint prosthesis; foot implant

Richard D. Koenig, DPM, FACFAS2
Lon R. Horwitz, DPM3

The Biomet Total Toe System (Fig. 1), formerly known as the Koenig Total Great Toe Implant, has been utilized as a first metatarsophalangeal replacement system for the past 5 years, with promising results (1, 2).  The system consists of a two-component joint replacement for the first metatarsophalangeal joint.  Every task of the surgery has a specifically designed instrument to aid the surgeon for preparation and installation (Fig. 2).
This system of implant arthroplasty is indicated for the reconstruction of degenerative, traumatic arthritis, severe hallux (abducto) valgus with loss of articular cartilage, hallux rigidus, dislocated first metatarsophalangeal joint (with or without a hypertrophied medial eminence of the first metatarsal head), and failed resection arthroplasty with or without previous inclusion of a silicone estastomer implant.  By selecting the appropriate surgical management for these pathologic joint destructive entities, painful loss of motion may be repaired within the great toe joint.
Contraindictions for this surgical method include advanced osseous demineralization, advanced osteoporosis, the severe vascular or medically compromised patient, the insensitive foot, osteomyelitis, and/or chronic sepsis.  While age of patient is not a primary consideration, certain parameters should be considered.
Very young patients should only be considered candidates for this procedure when the joint status is so severe that loss of function is eminent.  In elderly patients, who are otherwise in good health, activity levels should dictate the choice of this procedure.


Methods and Materials


The materials employed in the Biomet Total Toe System have been patterned from those materials found to be most compatible with the human body from orthopedic utilization in larger joints of the body.  Surgeons of the hip, knee, and more recently, the shoulder and elbow, prefer cobalt/chrome alloy in their replacement procedures due to its excellent wear resistance properties (3).  These surgeons have also found pure medical grade titanium to have increased compatibility for osseointegration with bone.4
The nonconstrained design of the Biomet Total Toe System features anatomical accuracy.  The most significant design feature includes replication of the plantar condyles of the first metatarsal for weightbearing articulation with the sesamoids.  By re-establishing the physiologic stabilizing structures of the first metatarsophalangeal joint, a balanced and efficient functional apparatus is more likely to result than by using a one-piece hinged implant (2).
The components of this nonconstrained, anatomically designed system consist of two modules of four different sizes.  The sizes: xs, s, m, and l may be used in appropriate combination (modular) to accommodate structural variances of the metatarsophalangeal dimensions.  The metatarsal component is a cobalt/chrome composition with all the bone contact surfaces coated with a porous titanium (medical grade) plasma sprayed layer for osteointegration5 (Fig. 3).

The phalangeal component is composed of ultra high molecular weight polyethylene (UHMWPE).  This material UHMWPE has been recognized, as in hip and knee surgery, as the material which is most compatible with the advantageous cobalt/chrome counterpart (4).  Bonebearing surfaces of the stem and interface have a roughened titanium surface for osseointegration, however, the polyethylene component is also available without a titanium back.  The option allows the surgeon to judge the phalangeal bone quality and select the appropriate component.  It is recommended that all the polyethylene component be fixed with bone cement.  Higher density bone should receive the polyethylene/titanium component.
Over a 5-year period, 61 cases were managed surgically by employing the Biomet Total Toe System (Figs. 1-3).  
Fifty cases utilized the cobalt/chrome with titanium porous coated component and UHMWPE with titanium-bearing surface component, and 11 cases utilized the cobalt/chrome with titanium porous coated metatarsal component with the all polyethylene phalangeal component 
(Fig. 1).
 

Figure 1  Components of the Biomet Total Toe System

Figure 2  Instrumentation of the Biomet Total Toe System

Figure 3  Biomet Total Toe component:  cobalt/chrome metatarsal with all polyethylene phalanx.

Of the 61 cases, 49 had a diagnosis of hallux rigidus and 12 had a diagnosis hallux (abductor) valgus.  Ten cases involved revision of failed SILAS TICâ6 elastomer implant arthroplasty (with diagnostic signs of pain and swelling for more than 1 year). Within this group of 61 cases, 4 had previous hallux (abducto) valgus surgery.  There were 41 females, 2 of which ad bilateral surgery and 18 males in this study.  The patients age ranged from 29 to 72 years, with a mean of 54.5 years.  All cases involved end stage arthroses.

Results

In an attempt to evaluate the results of the Biomet Total Toe System, a scoring method was devised, known as the Koenig Score.  This scoring method is patterned from the widely accepted Harris Hip Score.  The HHS in a pre- and postoperative scoring system designed to assess a patient’s improvement, both objectively and subjectively, following surgical repair of a diseased on traumatized hip (5).  Koenig patterned the pre- and postoperative score to objectively and subjectively assess the patient’s level of improvement following implant arthroplasty of a degenerative great toe joint.  The Koenig Score is not procedure-specific; that is, it may be useful for not only the Biomet Total Toe System arthroplasty, but may be applied to all surgical management procedures involving the first metatarsophalangeal joint.
Based on an overall 100-point rating, the Koenig Score has four categories for evaluation:  PAIN, FUNCTION, RANGE OF MOTION, and RADIOGRAPHIC evaluation (Fig. 4).  The sliding scale score is instituted preoperatively and postoperatively. The scores are then compared, noting the patient’s subjective evaluations regarding PAIN and FUNCTION levels, and the objective evaluations regarding RANGE OF MOTION and RADIOGRAPHIC evaluation by the investigator/surgeon.
 

                       Score among the four categories

1. Pain

                                                40 Points

2. Function

                                                30 Points

3. Rang Of Motion   

                                                20 Points

4. Radiographic Evidence Of Joint Deformity

                                                10 Points

 



Total 100 Points

Figure 4. The Koenig Score sheet

The PAIN category ranges from 0 to 40 points, with 0 representing constant pain on any movement and 40 points representing painfree motion.  The FUNCTION category ranges from 0 to 30 points with 0 for no function and 30 points for full fuction.  The RANGE OF MOTION category ranges from 0 to 20 points, where 0 is noted as no motion and 20 points for full range of motion.  The RADIOGRAPHIC evaluation ranges from 0 to 10 points.  Here, 5 radiographic signs (hallux valgus/varus, joint space narrowing, osteophyte/ectopic bone, sesamoid irregularity, and osteochondral defect) are evaluated by assigning 0 points for each sign that is appreciated and 2 points for the absence (can be a result of surgical resolution) of each of these 5 entities (Fig. 4).
 
To begin the score, the patient evaluates his/her preoperative clinical presention by placing a numerical assessment in the areas provided concerning PAIN and FUNCTION.  Next, RANGE OF MOTION of the involved first metatarsophalangeal joint is measured.  An assessment of the preoperative radiographs is also performed by the investigator/surgeon.  Once the patient has made relatively full recover, not less than 1 year postoperatively, this scoring process is repeated.  The two relative values are then compared, providing a reproducible assessment of the postoperative benefits.
 
The Koenig Score was employed in 61 cases of first metatarsophalangeal joint implant arthroplasty with the Biomet Total Toe System over a 5-year period.  Overall, 51 cases reported excellent results, with 10 cases having various levels of compromised results (Fig. 5).  In Fig. 5, the qualifiers that contribute to a compromised result are presented under each level of result.  The average preoperative Koenig Score was 31.7, whereas the average postoperative Koenig Score was 88.0.  No postoperative infections were identified.  There were no differences reported by those who received the titanium-backed phalangeal component versus the unbacked UHMWPE phalangeal component regarding PAIN, FUNCTION, or RANGE OF MOTION assessments.  
 

Figure 5  Four levels of results: Sixty-one cases utilizing the Biomet Total Toe System, based on the Koenig Score.  (The number in parentheses refers to the appropriate category assessment (1-4) of the Koenig Score.)

Of the cases in this study of the Biomet Total Toe System 83.5% were assessed with excellent results.
 

Discussion


Generally, the patients tolerated the surgery well with reduced pain and increased range of motion at the first metatarsophalangeal joint, post implantation.  Fifty-one cases in this study achieved a stable joint with adequate range of motion and thereby returned to the usual presurgical activities.  All of the patients achieved a functional weightbearing great toe joint, without sesamoid proxoid proximal drift.  Ten cases had their range of motion assessed as less than ideal; however, these patients did not express displeasure at the time of postsurgical evaluation.  This decreased range of motion may be attributed to years of a malfunctioning flexor hallucis brevis apparatus while the deformity was in the process of developing.  Four cases from the ten SILASTIC® elastomer implant failure revisions required a second revision with the Biomet Total Toe System.  This was attributed to poor host bone quality (2).  It did give an opportunity to examine the Biomet Total Toe components after more than 1 year.  In the four cases that were revised, evidence of wear debris was not present, now was there surface scratching of the articular surfaces noted.  Metallos (titanium oxide crystals) were identified in the synovial tissues of three case revisions, but were asymptomatic to these patients.  Additionally, there were no implant dislocations, significant foreign body reactions, implant pressure necrosis in host bone, ectopic formation of bone, fatigue fracture, subchondral cystic changes, or surrounding bone absorption appreciated postoperatively.  These potential complications are not uncommon sequelae reported with SILASTIC® elastomer hinge implant procedures (6).

Conclusion


The Biomet Total Toe System, from 61 cases over 5 years, appears to be a valuable means of restoring the diseased first metatarsophalangeal joint to pain free function and acceptable appearance.  Since the Koenig Score was developed and first implementation in 1990, it has been shown to produce a rapid and easy reference for demonstrating postsurgical improvement.  It is posed that the Biomet Total Toe System should be considered when reconstructing a pathologic first metatarsophalangeal joint.  It is especially useful when managing a failed SILASTIC® implant arthroplasty.  Additional studes with the Biomet Total Toe System are encouraged, as well as appropriate application of the Koenig Score method to quantitatively assess postoperative results.
 

References


1.       Koenig, R.D. Koenig total great toe implant, a preliminary report.  J.Am. Podiatr. Med. Assoc. 80:462-468, 1990.

2.       Koenig, R.D. Revision arthroplasty utilizing the Biomet Total Toe System for failed silicone elastomer implants.  J. Foot Ankle Surg. 33:222-227, 1994.

3.       Cohen, J. Metal Implants: Historical Background and Biological Response to Implantation, Biomaterials in Reconstructive Surgery, pp. 46-61, CV Mosby Co., St. Louis, MO, 1983.

4.       Mench, J., Amstatz, H. Knee morphology as a guide to knee replacement.  Clin. Orthop. 112:231-241, 1975.

5.       Harris, W. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. J. Bone Joint Surg. 51A: 737-755, 1969.

6.       Hetherington, V., Mercado, C., Karloc, L., Grillo, J. Silicone implant arthroplasty: a retrospective analysis.  J. Foot Ankle Surg. 32:430-433, 1993.


Additional References


Drago, J., Jacobs, A., Oloff, L.  A comprehensive review of hallux limitus.  J. Foot Surg. 23:213-220, 1984.
Hetherington, V., Carnett, J., Patterson, B. Motion of the first metatarsal phalangeal joint.  J. Foot Surg. 28:13-19, 1989.
Lewis, G., Alva, P. Stress analysis of the flexible one piece type first metatarsophalangeal joint implant.  J. Am. Podiatr. Med. Assoc. 83:29-38, 1993.
Shereff, J.J., Begjiani, F.J., Kummer, F.J. Kinematics of the first metatarsal phalangeal joint.  J. Bone Joint Surg. 68:392-398, 1986.